UBE3A and cancer: In strong contrast, E6AP silencing in HPV-negative, p53 wildtype RKO, HCT116, and U2OS cancer cells did not result in an appreciable increase in senescence (S1A Fig, upper panels for each cell line), and led to an only weak increase of p53 and p21 levels (S1B Fig) and a weak decrease in colony formation capacity, if at all (S1A Fig, lower panels for each cell line).